1. Field
The present disclosure relates generally to adhesion to surfaces and, in particular, to vacuum adhesion to surfaces. Still more particularly, the present disclosure relates to a method and apparatus for forming a vacuum adhesion between a number of seals and a surface while optionally allowing relatively free motion along the surface.
2. Background
Different types of attachment systems may be used to attach a platform to a surface. The platform may be, for example, a stage, a robotic machine, a robotic crawler, a vehicle, a mobile structure, or some other type of platform. Some platforms, such as, for example, but not limited to, robotic machines, may use vacuum systems to attach to a surface.
For example, a robotic machine may have one or more legs and a vacuum system associated with these legs. Further, one or more seals may be attached to the legs. The vacuum system may create at least a partial vacuum between the seals and a surface to form a vacuum adhesion with the surface. This vacuum adhesion may allow the robotic machine to move along a surface, while remaining attached to the surface. In particular, the robotic machine may move along a vertical surface, a horizontal or tilted surface, or some other angled surface without falling off the surface when the vacuum adhesion is formed between the seals on the robotic machine and the surface.
With these types of vacuum systems, a cushion of air is formed between the seals and the surface during operation of the vacuum system. In other words, a gap is present between the seals and the surface. The gap between the seals and the surface allows the seals to float above the surface while the downward force provided by the vacuum system allows wheels on the robotic vehicle to remain in contact with the surface. In this manner, the robotic machine may obtain traction on the wheels, which may be attached to motors that propel the robotic machine in a given direction. Consequently, the robotic machine may adhere to the surface and move along the surface with a reduced amount of friction between the robotic machine and the surface.
The width of the gap between the seals and the surface may determine the strength of the vacuum adhesion formed between the robotic machine and the surface. When the gap is wider than some selected threshold, the vacuum adhesion may not have the desired level of strength. Consequently, the robotic machine may lose traction and be unable to climb a vertical surface or may fall off the surface. When the gap is narrower than some selected threshold, the vacuum adhesion may be stronger than desired. Consequently, the robotic machine may be stuck to the surface and unable to move along the surface.
With some currently available vacuum systems, the width of the gap formed between the seals of the robotic machine and the surface may change as the robotic machine moves along the surface when the surface is not flat and/or has inconsistencies. For example, the surface may be a curved surface, such as the outer surface of a fuselage of an aircraft. In some cases, the surface may have inconsistencies such as, for example, without limitation, protrusions, protruding fastener joints, and/or other types of inconsistencies that may affect the width of the gap as the robotic machine moves over the surface.
A curved shape, curved features, surface inconsistencies, and/or other feature that make a surface not flat may cause the strength of the vacuum adhesion formed between the robotic machine and the surface to fluctuate as the robotic machine moves over the surface. Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.